John Prescott arrives at the QE2 conference centre in London to give evidence to the Iraq Inquiry. Photograph: Lewis Whyld/Press Association

The former deputy prime minister, Lord Prescott, has described how he had doubted intelligence reports about Iraq before the invasion but dismissed what he called "fashionable" criticism of Tony Blair for taking the country to war.

Offering fresh insights into the run-up to the invasion, he told the Chilcot inquiry: "When I kept reading them [intelligence reports], I kept saying to myself, 'Is this intelligence?' It was not very substantiated but clearly was robust."

Joint Intelligence Committee assessments contained conclusions "based too much on too little evidence, that was my impression at the time," he said. There was "a bit of tittle tatttle there, and a bit of judgment here".

Prescott said he felt "nervous" about the notorious claim in the government's September 2002 dossier that Saddam Hussein could launch weapons of mass destruction within 45 minutes. He said he adopted a sceptical approach but was not in a position to say to intelligence chiefs: "You are wrong."

He had asked Robin Cook, former foreign secretary then leader of the Commons, not to resign but said: "In the end of the day he was right." He admitted that Baroness Manningham-Buller, the former head of MI5, warned after the invasion in 2003 of the increased danger of a terrorist attack, but suggested she was simply trying to obtain additional funding for MI5.

He did not see private letters Tony Blair wrote to President George Bush at the time, but said the Labour prime minister persuaded the US administration to go down the UN route of diplomacy. The inquiry panel reminded Prescott he had written there was "no alternative but to stick by America". "If you look at the Falklands we could not have done that without American assistance," Prescott replied, referring to US satellite intelligence during the 1982 conflict.

It had been wrong for the government to blame French president Jacques Chirac for the breakdown of negotiations in the UN. "The French easily come to mind in the Brits' mind when we want to blame people," he said. "There is a lot of history for that."

Prescott did not think the cabinet should have been shown the detailed advice of the then attorney general, Lord Goldsmith, on the legality of the conflict. "All I wanted to know, and I think the Cabinet and the prime minister, is is it legal and can you legally justify military intervention? He said yes."

Dismissing as fashionable criticism of Blair, he said: "True leadership is not about having the benefit of hindsight. It is about having the gift of vision, courage and compassion, and I believe that Tony Blair had all those three."

Inquiry chairman Sir John Chilcot said his team hoped to visit Iraq "to see for ourselves the consequences of UK involvement" before publishing its final report around the turn of the year.